Reserve does not work

[DAVINCI]

Solder the curved slot closed, polish it flat & smooth, remove O-ring from diaphragm plunger.

Now, ON is ON, RESERVE is RESERVE and PRIME is OFF.

[DGXSER]

The one piece left of this puzzle, you say PRIME works, but, does PRIME Drain the tank dry? Or only down to the same level as ON?

If it drains the tank dry, I have no frickin clue. If it drains to the same level as ON, then there has to be some gunk blocking the lower portion of the filter.

[clcorbin]

Originally Posted by DGXSER

The one piece left of this puzzle, you say PRIME works, but, does PRIME Drain the tank dry? Or only down to the same level as ON?

If it drains the tank dry, I have no frickin clue. If it drains to the same level as ON, then there has to be some gunk blocking the lower portion of the filter.

IF I remember the last time I tested this thing, they all drain down to the same point. That test was last summer, so I am SURE I have forgotten something!

I think I will pull the petcocks this weekend and remove the filter screen to see what in the heck is going on behind the curtain. I agree with you, something has to be blocked, but then I REALLY get a headache when I realize that prime DOES work when the tank is above the "cutoff" level.

[ViperRon]

+1 on the mod suggested by DAVINCI as it is a definate preventative measure for bad gas water etc that can cause floats valves to stick open.

The filter screens can become very brittle. I am not sure about the condition of yours. I know that when I cleaned my petcocks I had trash in both the reserve and normal ports of the petcock that would not rinse or even spray out with carb cleaner. Like mentioned before I used the small braided wire that is used to hang pictures. Once the vacume assembly is out it all cleans easily. If bent into a sharp turn the wire loop will slide into the ports and has enough spring action to scrub the sides. If you cut about a foot and fold it over it will easily go threw the port up into the filter assembly. Using an electric drill makes fast work of anything in the ports and will polish the heavy corrosion out. If you want it squeekly clean you can soak it. If your filters come out easy great but I know mine would have broken and no one sells the correct filter cheap.

[BackRoadBiker]

Originally Posted by clcorbin

Before I take the next step and modify the filter towers, I figured I would see what anyone else has found. My problem: Reserve doesn't draw fuel down any lower than on mode due. Here is what I know:

• 1979 Standard with stock tank and petcocks
• Both petcocks has been cleaned and rebuilt
• Both petcocks flow gas in "On", "Res" and "Prime"
• When it stutters and hits the out of gas in "On", switching to reserve makes no difference.

Here is what I have done so far:

• Cleaned and rebuilt both petcocks
• Cleaned the filter screen with a light scrub brush and ligh solvent
• Visually inspected the screen and fuel ports
• Blew out the ports with compressed air while rebuilding the petcocks.
• Cussed.
• A LOT!

So far, nothing I have done has made a bit of difference. When I hit the 4.0 to 4.1 gallon used mark, it starts to stutter and try to run on two cylinders. Less than five miles after that, I'm pushing! And it makes no difference if the petcock is in "On", "Res", or "Prime" mode, it behaves the same. I THINK the Standard has a 5.5 gallon tank, so only getting 4 gallons usable is a bit ridiculous.

What I am planning on doing is modifying the screen so it can draw fuel from just above the bottom of the tank. I run inline filters, so I am not too worried about crap in the tank (and the tank was cleaned with electrolysis last year). This should give me closer to 5 gallons usable, which is a 25% increase in range over what I have now.

Before I do that, has anyone else fought this battle and won? If so, would you be willing to share your tactics? I would REALLY rather have a working reserve...

I have fought many battles with those feul percocks. Fortunately I have many spares. Your problem is a bit different, but what jumps out at me is the posibility of feul leaking beneath your plastic filters, thus by-passing reserve. If that was the case though, you should be able to put over 5 gals. in, unless the leakage is so gradual that it isn't feeding the engine. In which case, you end up pushing it. Also If the bike has set a long time with just a bit of feul in the tank, sediment could have the reserve portion of the filters partially plugged, and the result could be the same. New ones run about $30 a piece.. We know there is a left and right petcock. It has been a long time since I wrestled with mine, and I wonder if U may have accidently got the handle pieces reversed.. Just off the top of my head thoughts. Wish I could do better..

[clcorbin]

Originally Posted by BackRoadBiker

We know there is a left and right petcock. It has been a long time since I wrestled with mine, and I wonder if U may have accidently got the handle pieces reversed.. Just off the top of my head thoughts. Wish I could do better..

Actually, I can say with 100% certainty the handles are NOT swapped left to right. Here is why: if the handles where swapped, based on the pictures above, we can work out the behavior of the petcock:

On Position - Normal port is connected to vacuum port (same as correct handle), but reserve would be connected to the bypass port. This would behave pretty much exactly like the "correct" setup in the prime position. Gas would flow with out the engine running.

Prime Position - Plugged port connected to the vacuum port and the normal power connected to the reserve port. AKA: No gas flow unless there is a leak!

Reserve Position - Reserve port is connected to vacuum port, bypass port connected to plugged port. This position would work exactly like the reserve position of the correct setup.

My prime position does work, so I KNOW that the handles have to be in the correct position. On the bright side, those pictures sure did make me think about exactly what is going on inside those petcocks!

[BackRoadBiker]

After seeing those pics. They need a total rebuild.. I keep at least one left and one right on hand all shined up with new guts and ready too install, they work on both my XS-11 E & F.. For a rebuild kit go too
http://stores.ebay.com/GEORGEFIXS-MO...&submit=Search

[BackRoadBiker]

Originally Posted by DGXSER

The one piece left of this puzzle, you say PRIME works, but, does PRIME Drain the tank dry? Or only down to the same level as ON?

If it drains the tank dry, I have no frickin clue. If it drains to the same level as ON, then there has to be some gunk blocking the lower portion of the filter.

Do what I did; Make a thorough study of the Feul Valves. Starting with the feuls path, as it flows through the ports of the feul valve. Make sure too notice how the pathway changes as the valve is turned in each direction, between "On, Prime, and Reserve." Ofcourse we know "On", becomes Off", when the engine shuts down and there is no vacumm pulling it open.. (If one doesn't shut completely off, the drippage can over power the needle valves in the carbs. and you will see gas under the bike, especially when the tank is full.) All ports and surfaces must be well cleaned and polished. The diphram, gaskets, and seals must all be like new too avoid leakage.. Interestingly enough.. I put approx. 100,000 miles on my orig. XS-!!E, that I bought new in 78, and never learned anything about the feul percocks, simply because they never gave me any trouble at all.. When I bought the 2 that I presently own, it became a whole different story, because the years had taken their toll. *Beaware also that; If the bike sits awhile and the feul valves don't get excersized, it is not uncommon to turn the lever and have it tear the big gasket. Especially if it sits in the sun and drys out.. I have had the parts stick together.. Good Luck..

[Rasputin]

Originally Posted by BackRoadBiker

After seeing those pics. They need a total rebuild.. I keep at least one left and one right on hand all shined up with new guts and ready too install, they work on both my XS-11 E & F.. For a rebuild kit go too
http://stores.ebay.com/GEORGEFIXS-MO...&submit=Search

I am presuming you mean the petcock pics I posted. They are in a pile of parts that have not yet been dealt with. Yes they definetly need a rebuild. The rubber gasket with the four holes in it was so brittle I could hardly get it out without breaking it. That in its self may be a clue as to why the problem is there at all. We all only have the info provided by the guy doing the work, the rest is simply guesswork on our part. I think we all need some pics from the OP and then we can maybe help more. The fact that BackRoadBiker could see that mine needed rebuild is a point made.

[BackRoadBiker]

By the curved slot, do you mean the elongated slot on the back of the lever cock? If so, by soldering that closed and polishing it off smooth, you would create a condition where no feul would flow from the tank too the carbs., at all.. Because that elongated slot is the channel the feul travels through.. Maybe I am misunderstanding something, but these feul valves have really put me through the course.. I have had 4 of them fail in several different ways, on many occasions and I can say for a fact, they are unique little rascals, designed too work only one way, that really put me too the test. I don't think there is much more I can learn about them, but I'm willing too try, and many times I wished they had a manual off position. Some times when gas was running on the floor and some times when it was running down my pant legs..LOL..

[natemoen]

Originally Posted by BackRoadBiker

many times I wished they had a manual off position.

Manual off. File off the little tab at the top of the front plate with the position names stamped on it, file the petcock handle down a hair (just enough to clear the tank) and then straight up becomes a manual off position. Takes 10 minutes.

[BackRoadBiker]

Well I just checked that idea out with a disassembled petcock in my hands, and I guess that would work, as long as the engine wasn't running, but if left in that position and started, the vacumm chamber would open an attempt too suck feul out of the carbs...? Not sure how good that would be? I guess as long as the diaphram was solid, it may not be a problem at all.. I'm still amazed at how trouble free these things were on my original XS-11 E, that I bought new in 78, and ran up too about 100,00 miles in the folowing years. I guess it shows the goodness of newness verses the toll the years can take on some things. These petcocks are still available new for around $140, a piece. I have spares for both sides, from a salvage yard, and some extra rebuild kits, but my patients are wearing thin.. Thanks, for your imput..

[tom clisham]

Originally Posted by natemoen

Manual off. File off the little tab at the top of the front plate with the position names stamped on it, file the petcock handle down a hair (just enough to clear the tank) and then straight up becomes a manual off position. Takes 10 minutes.

I like this. Going to put a standard tank on 1 of my specials & I'll definely do this 1.

I have'nt followed this whole thread. BUT< I hope it's been noted somewhere that reserve only flows when bike is running, just like ON.

[cywelchjr]

Originally Posted by BackRoadBiker

By the curved slot, do you mean the elongated slot on the back of the lever cock? If so, by soldering that closed and polishing it off smooth, you would create a condition where no feul would flow from the tank too the carbs., at all.. Because that elongated slot is the channel the feul travels through.. Maybe I am misunderstanding something, but these feul valves have really put me through the course.. I have had 4 of them fail in several different ways, on many occasions and I can say for a fact, they are unique little rascals, designed too work only one way, that really put me too the test. I don't think there is much more I can learn about them, but I'm willing too try, and many times I wished they had a manual off position. Some times when gas was running on the floor and some times when it was running down my pant legs..LOL..

That elongated slot only enables the prime funtion, the on and reserve funtions go through the straight slot. So filling the curved slot and removing the o-ring from the diaphragm plunger makes the petcock no longer vacuum operated and makes prime into off and on really on and reserve really reserve but makes them run whether the engine is on or not. I've been working with these petcocks for 24 years now, as these are the same as the XS400 has (only the right side one is reversed), so I'm pretty well versed in them as well.

As for if the filling the curved slot works, the proof is in the pudding as they say, DAVINCI on here has been running his bike with his petcocks modified like that for quite some time with no problems and no leaks. He did it because he got tired of the leaking and such and now he just remembers to always turn them off when he parks the bike.

[cywelchjr]

Originally Posted by BackRoadBiker

Well I just checked that idea out with a disassembled petcock in my hands, and I guess that would work, as long as the engine wasn't running, but if left in that position and started, the vacumm chamber would open an attempt too suck feul out of the carbs...? Not sure how good that would be? I guess as long as the diaphram was solid, it may not be a problem at all.. I'm still amazed at how trouble free these things were on my original XS-11 E, that I bought new in 78, and ran up too about 100,00 miles in the folowing years. I guess it shows the goodness of newness verses the toll the years can take on some things. These petcocks are still available new for around $140, a piece. I have spares for both sides, from a salvage yard, and some extra rebuild kits, but my patients are wearing thin.. Thanks, for your imput..

That vacuum chamber does try to suck anything, it's just a valve opening. With the lever in the up position the slots don't connect to any port that connects to the tank, so no fuel can flow. This mod was discovered by psycoreefer on here and several members have successfully made and used the mod, again the proof is in the pudding. Again, the vacuum when applied just pulls the diaphragm back pulling the plunger back from the seat so that the o-ring no longer seals the passage to the fuel line so fuel can flow, and with the lever up, the slots don't connect to either of the two fuel ports in the tank, thus preventing any fuel flow.